What Is Physics?

The word physics is derived from the Latin word physica, which means "natural thing."

According to the Oxford English Dictionary, physics is defined as:

Definition of "Physics" by the Oxford English Dictionary

"The branch of science concerned with the nature and properties of matter and energy. The subject matter of physics includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."

Definition of "Physics" by Microsoft Encarta

“A major science dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. Sometimes in modern physics a more sophisticated approach is taken that incorporates elements of the three areas listed above; it relates to the laws of symmetry and conservation, such as those pertaining to energy, momentum, charge, and parity.”

What these definitions indicate is that physics is a branch of science that deals with the properties of matter and energy and the relationship between them. It also tries to explain the material world and the natural phenomena of the universe.

The scope of physics is very wide and vast. It deals with not only the tinniest particles of atoms, but also natural phenomenon like the galaxy, the milky way, solar and lunar eclipses, and more. While it is true that physics is a branch of science, there are many sub-branches within the field of physics. In this article, we will explore each of them in depth.

What Are the Branches of Physics?

While there are more branches sprouting up as science and technology progresses, there are generally 11 branches of physics. These are as follows.

Branches of Physics

Classical physics

Modern physics

Nuclear physics

Atomic physics

Geophysics

Biophysics

Mechanics

Acoustics

Optics

Thermodynamics

Astrophysics

Continue reading to explore each of these branches in depth.

1. Classical Physics

This branch of physics is mainly concerned with the laws of motion and gravitation as outlined in Sir Isaac Newton and James Clark Maxwell’s kinetic theory and thermodynamics, respectively. This branch of physics deals mostly with matter and energy. Often, physics which date before 1900 are considered classical physics, whereas physic which date after 1900 are considered modern physics.

In classical physics, energy and matter are considered separate entities. Acoustics, optics, classical mechanics, and electromagnetics are traditionally branches within classical physics. Moreover, any theory of physics that is considered null and void in modern physics automatically falls under the realm of classical physics.

As Newton's Laws are one of the main features of classical physics, let's examine them.

What Are the Three Laws of Physics?

The three laws of physics, as they are commonly referred to, are known formally as Newton's laws of motion. They are considered the basis of classical mechanics. Newton's laws describe the motion of a body upon which forces may act and which may exert forces on other bodies.

When we speak of bodies, we are not speaking of actual human bodies (although human bodies can be included in this definition), but of any piece of matter upon which a force may act. Newton's three laws are outlined below.

Newton's Laws of Motion (The Three Laws of Physics)

Law of Inertia: A body remains at rest or in uniform motion in a straight line unless acted upon by a force.

Force = Mass x Acceleration: A body's rate of change of momentum is proportional to the force causing it.

Action = Reaction: When a force acts on a body due to another body, then an equal and opposite force acts simultaneously on that body.

The Three Laws of Physics Explained (Video)

2. Modern Physics

Modern physics is a branch of physics that is mainly concerned with the theory of relativity and quantum mechanics.

Albert Einstein and Max Plank were the pioneers of modern of physics as the first scientists to introduce the theory of relativity and quantum mechanics, respectively.

In modern physics, energy and matter are not considered as separate entities. Rather, they are considered different forms of each other.

What Are the Two Pillars of Modern Physics?

The two pillars of modern physics are as follows.

Albert Einstein's theory of relativity

Max Plank's quantum theory.

What Is the Theory of Relativity?

Albert Einstein's theory of relativity is one of the most important discoveries of the contemporary age, and states that the laws of physics are the same for all non-accelerating observers. As a result of this discovery, Einstein was able to confirm that space and time are interwoven in a single continuum known as space-time. As such, events that occur at the same time for one observer could occur at different times for another.

Einstein's theory of relativity is summarized in the formula:

E = mc^2

In this equation, "E" represents energy, "m" represents mass, and "c" represents the speed of light.

Einstein's Theory of Relativity Explained (Video)

What Is Quantum Theory?

Discovered by Max Plank in 1900, quantum theory is the theoretical basis of modern physics that explains the nature and behaviour of matter and energy on the atomic and subatomic level. The nature and behaviour of matter and energy at that level is sometimes referred to as quantum physics and quantum mechanics.

Plank discovered that energy exists in individual units in the same way that matter does, rather than just as a constant electromagnetic wave. Thus, energy was quantifiable. The existence of these units, called quanta, act as the basis of Plank's quantum theory.

3. Nuclear Physics

Nuclear physics is a branch of physics that deals with the constituents, structure, behaviour and interactions of atomic nuclei. This branch of physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons.

According to the Microsoft Encarta encyclopedia, nuclear physics is defined as:

“The branch of physics in which the structure, forces, and behaviour of the atomic nucleus are studied.”

In the modern age, nuclear physics has become very wide in its scope and has been applied in many fields. It is used in power generation, nuclear weapons, medicines, magnetic resonance, imaging, industrial and agricultural isotopes, and more.

Who Discovered Nuclear Physics?

The history of nuclear physics as a distinct field from atomic physics begins with the discovery of radioactivity by Henri Becquerel in 1896. The discovery of the electron one year later indicated that the atom had an internal structure.

With this, studies began on the nuclei of atoms, thus nuclear physics was born.

Nuclear physicists examine only the nucleus, not the atom as a whole. | Source

4. Atomic Physics

Atomic physics is a branch of physics that deals with the composition of the atom apart from the nucleus. It is mainly concerned with the arrangement and behaviour of electrons in the shells around the nucleus. Thus, atomic physics mostly examines electrons, ions, and neutral atoms.

One of the earliest steps towards atomic physics was recognizing that all matter is comprised of atoms. The true beginning of atomic physics is marked by the discovery of spectral lines and the attempt to explain them. This resulted in an entirely new understanding of the structure of atoms and how they behave.

5. Geophysics

Geophysics is a branch of physics that deals with the study of the Earth. It is mainly concerned with the shape, structure and composition of the Earth, but geophysicists also study gravitational force, magnetic fields, earthquakes, magma, and more.

Geophysics was only recognized as a separate discipline in the 19th century, but its origins date back to ancient times. The first magnetic compasses were made from

All of these discoveries can be included in the field of geophysics, which is defined as:

"a natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis."

Computer simulation of the Earth's magnetic field in a period of normal polarity between reversals. | Source

6. Biophysics

According to the Microsoft Encarta encyclopedia, biophysics is defined as:

“the interdisciplinary study of biological phenomena and problems, using the principles and techniques of physics.”

Biophysics studies biological problems and the structure of molecules in living organisms using techniques derived from physics. One of the most groundbreaking achievements of biophysics is the discovery of the structure of DNA (Deoxyribonucleic Acid) by James Watson and Francis Crick.

Poll

Physics is the study of:

7. Mechanical Physics

Mechanical physics is a branch of physics that deals with the motion of material objects under the influence of forces.

Often called just mechanics, mechanical physics falls under two main branches:

Classical mechanics

Quantum mechanics

Classical mechanics deals with the laws of motion of physical objects and the forces that cause the motion, while quantum mechanics is the branch of physics which deals with the behaviour of smallest particles (i.e. electrons, neutrons, and protons).

What Are the Main Branches of Mechanics?

Mechanics can be broken down into eight sub-branches. These are as follows:

Applied mechanics

Celestial mechanics

Continuum mechanics

Dynamics

Kinematics

Kinetics

Statics

Statistical mechanics

8. Acoustics

Hence, we can define acoustics as a branch of physics that studies how sound is produced, transmitted, received and controlled. Acoustics also deals with the effects of sounds in various mediums (i.e. gas, liquid, and solids).

9. Optics

Optics is a branch of physics that studies electromagnetic radiation (for example, light and infrared radiation), its interactions with matter, and instruments used to gather information due to these interactions. Optics includes the study of sight.

The Microsoft Encarta encyclopedia defines optics as:

“a branch of physical science dealing with the propagation and behaviour of light. In a general sense, light is that part of the electromagnetic spectrum that extends from X rays to microwaves and includes the radiant energy that produces the sensation of vision.”

Who Invented Optics?

Optics began with the creation of lenses by the ancient Egyptians and Mesopotamians. This was followed up by theories of light and vision developed by ancient Greek philosophers and the development of geometric optics in the Greco-Roman world.

These earlier studies on optics are known as classical optics. Studies that came after the 20th century, such as wave optics and quantum optics, are known as modern optics.

10. Thermodynamics

Thermodynamics is a branch of physics that deals with heat and temperature and their relation to energy and work. The behaviour of these quantities is governed by the four laws of thermodynamics.

Who Discovered Thermodynamics?

The field of thermodynamics was developed from the work of Nicolas Léonard Sadi Carnot who believed that engine efficiency was the key that could help France win the Napoleonic Wars.

The Scottish physicist Lord Kelvin was the first to come up with a concise definition of thermodynamics. His definition stated:

"Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency."

What Are the Four Laws of Thermodynamics?

The four laws of thermodynamics are as follows.

If two systems are in thermal equilibrium with a third system, they are in thermal equilibrium with each other. This law helps define the concept of temperature.

When energy passes, as work, as heat, or with matter, into or out from a system, the system's internal energy changes in accord with the law of conservation of energy. Equivalently, perpetual motion machines of the first kind (machines that produce work with no energy input) are impossible.

In a natural thermodynamic process, the sum of the entropies of the interacting thermodynamic systems increases. Equivalently, perpetual motion machines of the second kind (machines that spontaneously convert thermal energy into mechanical work) are impossible.

The entropy of a system approaches a constant value as the temperature approaches absolute zero. With the exception of non-crystalline solids (glasses), the entropy of a system at absolute zero is typically close to zero, and is equal to the natural logarithm of the product of the quantum ground states.

The Laws of Thermodynamics Explained (Video)

11. Astrophysics

The word "astrophysics" is a combination of two Latin-derived words: astro, which means "star," and phisis, whichmeans "nature."

Thus, astrophysics can be defined as a branch of astronomy which is concerned with the study of universe (i.e., stars, galaxies, and planets) using the laws of physics.

What Is the Difference Between and Astrophysicist and an Astronomer?

Technically speaking, astronomers only measure the positions and characteristics of celestial bodies, whereas astrophysicists use the application physics to understand astronomy.

However, the terms are now used interchangeably, since all astronomers use physics to conduct their research.

Comments

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Bootaan

2 days ago

Its good information , it helps me .

donaldlonungu@gmail.com

4 weeks ago

thank you so much

Nirmala

5 weeks ago

Thank you so much it is really helpful for my studies

om chavan

5 weeks ago

oh nice

olamide

6 weeks ago

good job, u really help alot

Oliver Karplah Gaye

6 weeks ago

Thank you so much for acknowledgment it helps people

Sundas

8 weeks ago

It really helped me thanks for the information!!!!!

Mohamed issa kargbo

2 months ago

it's important to solve mathematical problems

Angel

2 months ago

Thank you,very comprehensive

ezra

2 months ago

very thank you

Ahiafor Reuben Doe Kwame Junior

3 months ago

It has really helped me alot thanks for the information

Mujahed Ahmad

3 months ago

Thanks

hogwards

3 months ago

helped me alot for my assignment. i appreciate it!!!!!!!!!!!!!!!

Maryam

3 months ago

It is so good

It helped me very much to complete my assignment

Ameenu

3 months ago

This is the simplest explanation i have ever come across so far in physics, it is very easy to comprehend. thanks

rofiat suru

3 months ago

It really helped me thanks for the information

fasil mitku

4 months ago

thanx for the information

Chukwu Chiagozie Innocent

4 months ago

Thanx For Ur Help On This Great Discovery May God Reward U

yehoida

4 months ago

this is quite interresting and helpful but i have one question between all the types or branches of science which of them is more easier and nice to learn I'm asking because i want to know which course i want to master i was thinking about doing geoscience but im also seeing biology as an easy subject please help me , make the right decision before my time is up.

thanks

Aj

5 months ago

thanks for the info

AUTHOR

Muhammad Rafiq

5 months agofrom Pakistan

Thanks Victor Wllie for stopping by and commenting!

jonjie

5 months ago

this is so helpful thank you

Dr.Raaz

5 months ago

Interresting!that was wonderfull and helpfull.i really appreciate it

Israr...

5 months ago

Brilliant.

Johnny

5 months ago

That was really helpful

Sage

5 months ago

Interesting one, thank you for this.

Laraib. Malik

5 months ago

Thanxx for helpful information

Emmanuel (Uguru) Chidozie, University of PortHarcourt, Nigeria.

5 months ago

Sir, I am immeasurably grateful to you for your detailed treatment of Physics and it's various branches . It has greatly assisted me in my Ph.D.thesis.

Junaid

5 months ago

Great job thanks for guidance its helpfull

FRED MALENZHI

5 months ago

THANKS

pondamali mashaka

6 months ago

zeroth thermodynamic law show the relationship between heat and temperature!

Uchexcel

6 months ago

Thanks for this great job. But you did not include Solar energy Physics, Meteorological Physics , Statistical Physics, Medical Physics, Solid State Physics( Physics electronics), and Ionospheric Physics.

Joshua

6 months ago

why mathematics is the langguage of physcis?

samreen

6 months ago

This was really helpful... thankyou very much

Mithun

6 months ago

Easy to understand

Evelyn

6 months ago

Thanks

oyebanji Gbohunmi

7 months ago

The author tried he is so enlightened to impact knowledge ,but pls add many quiz to answer and scores .,prizes should also be awarded .thanks am so enlightened and grateful sir/ma

itsme_alexandrea

7 months ago

Is classical physics is one of the branches of physics?

if yes, my ghod! i thought that physics has only 10 branches.. and now? it's 11?

please anyone answer me..

Anshu

7 months ago

Nice introduction to physics

Raashid Rashid

8 months ago

This all was good but their should be a flow chart to understand much better

AUTHOR

Muhammad Rafiq

8 months agofrom Pakistan

Thanks for your comments. I am glad you liked it.

hareem Malik

8 months ago

Really all the definition and branches of physics explain vry well I am impressed love it......

Physics is a science that studies measurable magnitudes and the phenomena that transform them without changing their natures.

Hello

12 months ago

Hard but thx foe this

elithabeth

12 months ago

i hate it just kinding ilove it

Geoffrey kimani

13 months ago

Well summarised notes kudos

Filipino

13 months ago

It really Help me in my projects and Assignments in Science and Chemistry

Reeti

13 months ago

Thanks

Amini Abubakar

14 months ago

Masha Allah, that is nice

khan

14 months ago

Trll about laws of motion

amna saleem

14 months ago

Yes guys it really awesome

abeb

14 months ago

nice

Abdikarim

14 months ago

Thank you a lot

romel

15 months ago

thank you so much because its a big help to me as a student and also to the other :)

Kc burgess

15 months ago

I finally see the answer

Dara

15 months ago

Thank you

Mark wheaton

16 months ago

Good for research

buba barrow

16 months ago

i like the arrangment

AUTHOR

Muhammad Rafiq

16 months agofrom Pakistan

Thanks Topsy for your comments.

Topsy adrewson

16 months ago

I actually liked the way u broke down the definition and branches it really helped

Ehab Ahmad

17 months ago

I'd Like To Know,If There is A Direct Relation Between Physics And Psychology ?

(Mechanism of Depression,Nerves Disorder And How The Feelings Work) ?

AUTHOR

Muhammad Rafiq

17 months agofrom Pakistan

Thanks Hena for your feedback. I am glad it helped you.

AUTHOR

Muhammad Rafiq

17 months agofrom Pakistan

Thanks Adi Jones for stopping by and commenting.

Adi Jones

17 months ago

I love love your comment, I really do love this page ,good work

Hena Palay

17 months ago

I actually love this page. I've been searching a very long time now, but couldn't find what I wanted so easily. Now that this page displays everything exact as I wanted it. Am from Liberia and I love Physics. But find it difficult to understand by improper teaching.

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